Answer:
x = 3.25 or 3

Explanation:
The total length of the top side is equal to the total length of the bottom line. This means that:
x + 6.42 + 7.08 = 16.75
To find x, rearrange to make it the subject by subtracting the two on the side of x from the opposite side:
x = 16.75 - 6.42 - 7.08
x = 3.25
x = 3

Hope this helps!